ONICON System-30 BTU - Manual (Page 14)

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System-30 BTU Measurement System Manual 05/14 - 0667-2 / 18335
Page 14
3.3 ELECTRICAL INSTALLATION
All user supplied conduit fittings, junction boxes, etc. are to be installed as required by all
applicable building codes.
IMPORTANT NOTE
The System-30 BTU Measurement System is designed with one internal (Temp 1) and one remote
(Temp 2) temperature sensor. If the meter body is located in the supply pipe, then the internal
temperature sensor will indicate the supply temperature, and the remote sensor will indicate the
return temperature. This relationship will reverse if the meter body is located in the return pipe.
The location of the meter will also affect the logic used to determine mode 1 and mode 2 operations
for dual mode applications. Single mode energy measurements are absolute measurements and
are not effected by polarity of the Delta t.
i
3.3.1 Single Mode (4 Pipe) Vs. Dual Mode (2 Pipe) Operation
ONICON System-30 BTU Meters may be configured for single or dual mode applications.
Single and dual mode is a reference to the piping system and not the meter itself. Single
mode (4 pipes) applications are those that always have the same relationship between the
supply and return pipe temperatures. In dual mode (2 pipes) applications the polarity of
the temperature differential (delta-T) reverses, often on a seasonal basis.
It is often desirable to totalize the amount of energy transferred in each mode in separate
registers. For these applications, ONICON Btu meters may be configured for dual mode
operation. In this configuration, the meter will measure and totalize energy in separate
registers based on the polarity of the delta-T.
The drawings and tables on the next pages illustrate the relationship between meter
location, temperature sensor and mode of operation.